cooling question

[Hemi Joel]

As a test, you could just completely remove the shroud and then drive it down the highway and see how it does.

[WerbyFord]

Does the fan shroud block air flow when going down the road? I never understood those shrouds that are just about flat over the back of the radiator.

Anyone who thinks you can improve cooling by slowing down the water flow needs to move into the 21st century. That old wives tale was scientifically disproven years ago. If that theory were true, then you could also improve cooling by slowing down air flow, so the air would have more time to absorb the heat. So try running your fans on 6 volts to cool your engine better.

I suspect HemiJoel is right on both counts here:
* It cools fine at idle, heats up at speed = = airflow problem. Ditch the shroud / e-fans & just try no fan or a clutch fan, or even a fixed-blade, see if it cools better on the freeway.

* I think the Urban Legend about "you have to flow the water slower to give it time to cool" started from the Often-True Fact that when you take the thermostat OUT, the engine heats up more. Conclusion - more water flow is bad. But that's not what's happening. When you take the thermostat out, you de-pressure the block, causing steam hot-spots that run away & boil the water & overheat. More water flow is better, but you have to keep pressure in the block, so you want a choke point (the thermostat) right at the block exit. I find the best cooling of all is with a thermostat with the center cut out. Lots of flow, but a restriction ring to keep the block pressured.

BTW sixty9, do those Magnafows sound like good old glasspacks? Seems that's how theyre built so I wondered.

[6667fan]

Harry, have you mathed out your WP pulley time crank pulley ratio? A cheap experiment would be to get that ratio  to 1.25/1 or better. I agree on the idea that maybe what you have in front of the engine might be hurting you. Also agree with Ross that 215 is not the end of the world though I don’t feel comfortable seeing that on the gauge myself.
Someone mentioned a CVF wp pulley. I have one on the shelf. I can send it to you if you want to try it. It’s tiny, 5.4” O.D.
Email me
jwysocki@charter.net
or text 41 three/six 95-3one03

JB

[machoneman]

Does the fan shroud block air flow when going down the road? I never understood those shrouds that are just about flat over the back of the radiator.

Anyone who thinks you can improve cooling by slowing down the water flow needs to move into the 21st century. That old wives tale was scientifically disproven years ago. If that theory were true, then you could also improve cooling by slowing down air flow, so the air would have more time to absorb the heat. So try running your fans on 6 volts to cool your engine better.

I suspect HemiJoel is right on both counts here:
* It cools fine at idle, heats up at speed = = airflow problem. Ditch the shroud / e-fans & just try no fan or a clutch fan, or even a fixed-blade, see if it cools better on the freeway.

* I think the Urban Legend about "you have to flow the water slower to give it time to cool" started from the Often-True Fact that when you take the thermostat OUT, the engine heats up more. Conclusion - more water flow is bad. But that's not what's happening. When you take the thermostat out, you de-pressure the block, causing steam hot-spots that run away & boil the water & overheat. More water flow is better, but you have to keep pressure in the block, so you want a choke point (the thermostat) right at the block exit. I find the best cooling of all is with a thermostat with the center cut out. Lots of flow, but a restriction ring to keep the block pressured.

BTW sixty9, do those Magnafows sound like good old glasspacks? Seems that's how theyre built so I wondered.

Right Werby! I was going to post the same info but you said it better. Running virtually any engine w/o a thermostat or a sized plate that restricts the water flow is foolish. It's not the speed of the coolant but the need for some back pressure to cool hot spots in the heads, block, etc. Without some pressure, voids appear near some critical hot spots like those near the exhaust ports. In fact, roundy-round racers and other competitors do run various sizes of plates in lieu of a street type thermostat for that very reason.     

https://www.summitracing.com/parts/mor-63440?seid=srese1&gclid=EAIaIQobChMI2KXS0f-z6gIVSrzACh1I5Q7DEAQYASABEgJd6fD_BwE

[sixty9cobra]

I thought about removing the shroud as a test. I am only 2 blocks from a long road where I test my car lol 3 miles with no intersections, yes even in NY lol. I have no idea what the pulley ratio is but been running this combo since I was 16 that's more than 45 yrs. Only in the last 5 or so have I notice the high temps. I just usually avoid hot days or bite my tongue.

[Hemi Joel]

I agree with Werby and Macho on the pressure, plus there is one more factor. As stated, the water pump builds pressure against the restriction of the thermostat. Back in the old days of top tank radiators, low pressure caps, and no radiator overflow recovery system, if guys removed the thermostat, what was the next restriction? It was the radiator core. So at higher RPM, the pump is building enough pressure in the top tank of the radiator to push some of the coolant past the pressure cap. Less coolant = higher temps = the old, erroneous theory.

[Cyclone03]

Somebody please reply to this post, my reply’s here must not be showing up.
Seriously let me know if you see this.

[Bolted to Floor]

Somebody please reply to this post, my reply’s here must not be showing up.
Seriously let me know if you see this.

I see it!!

[Bolted to Floor]

Somebody please reply to this post, my reply’s here must not be showing up.
Seriously let me know if you see this.

[cjshaker]

Somebody please reply to this post, my reply’s here must not be showing up.
Seriously let me know if you see this.

You're just being ignored..lol 

Good advice though. Power Tour and Drag Week will weed out any cooling issues in a HURRY.

[Cyclone03]

Somebody please reply to this post, my reply’s here must not be showing up.
Seriously let me know if you see this.

You're just being ignored..lol 

Good advice though. Power Tour and Drag Week will weed out any cooling issues in a HURRY.

well a least somebody said it,thanks.
BTW the fan shroud needs some vent flaps the air is packing up inside it,the 2 fan holes are not big enough to let the air out.

Today I was in a parade ,rolling at about 5mph, 210deg 98f air temp.

[SReist]

For testing purposes and arguments sake, I would like to see a vacuum advance distributor. That made more difference than anything on my car. 69 Mach 1 428 CJ stroked to 447. Steve

[1967FEGT]

I thought about removing the shroud as a test. I am only 2 blocks from a long road where I test my car lol 3 miles with no intersections, yes even in NY lol. I have no idea what the pulley ratio is but been running this combo since I was 16 that's more than 45 yrs. Only in the last 5 or so have I notice the high temps. I just usually avoid hot days or bite my tongue.

I own a home up the Watkins Glen area. No shortage of open road and straight stretches.  I haven't taken my Shelby up yet but I fear the deer!

[sixty9cobra]

Somebody please reply to this post, my reply’s here must not be showing up.
Seriously let me know if you see this.

I get it  loose the shroud, still looking at options.

[sixty9cobra]

I have an update ordered the spring for the lower hose. I took the Focus fans out and installed my old stainless steel flex fan no shroud. Drove around last night never came off 160 degrees. I could feel the hot air coming out of the floor vents definitely moves a lot more air.. Cyclone03 was right. Ive been looking for shroud that holds two fans that will fit this radiator not much made. Maybe ill go back to a clutch fan. Its supposed to be in the mid 90s this weekend stay tuned.
                 Harry